In general, gliding sports or activities are recreational or competitive sports wherein a skier stands on one or two skis, and is pulled by a boat over the surface of the water or snow. Skis can be used for jumps, flips, speed, slalom turns and the like, with the feet one behind the other pointing in the same direction, next to each other pointing in the same direction, with the heels together and toes pointing in opposite directions, only one foot attached, etc.
Waterskiing was invented almost a hundred years ago, and the first patent, document U.S. Pat. No. 1,559,390, described skis with a simple rubber area for contact with the feet. With time, means for attaching the foot/feet to the ski were developed, such as by rubber cords (webbing or strap), then boots that were either attached to the ski, so that the skier's feet could slide in and out, or else placed on the feet and releasably (or temporarily) attached to the ski. Use of these two types of attachments allows better attachment of the ski to the skier, and thus better control of the ski.
The means for attaching the foot to a ski thus evolved in two different directions, flexible and hard-shell bindings. Flexible bindings generally comprise a boot held by a binding (normally of rubber and tissue) and fixed to the board. These flexible bindings are generally easier to produce and less expensive, but provide less control of the board. Hard-shell bindings comprise boots of hard injected plastic and favor the rigidity of the attachment between the foot and the board. Consequently, there is a risk of injury in case of a fall. To this end, automatic release systems may be provided to free the user's foot in case of a fall, to prevent or at least reduce twisting of joints.
FIG. 1 is a side view of a type of conventional hard-shell waterski binding system 1 comprising: a generally planar ski 2, a base plate 3, a front toe bar 4, a back release 5, and a boot 6, as disclosed by the U.S. Pat. No. 5,785,566 for example.
The ski 2 (or board) comprises a substantially planar top surface 2A directed towards the user and a substantially planar bottom surface 2B directed towards a gliding element (snow, water, sand, etc.). Likewise, the base plate 3 comprises a substantially planar top surface 3A directed towards the user and a substantially planar bottom surface 3B directed towards the ski 2, such that their respective surfaces 3B, 2A are in contact. The base plate 3 receives the front toe bar 4 and the back release 5, and is fixed to the board 2.
The boot 6 comprises a toe 7 and a heel 8 comprising a protrusion 8′. The boot may further comprise an inner liner, buckles to secure the boot around the foot, a hinge to open the boot for insertion of the foot, and so forth, not referenced. The user places the boot 6 on his or her foot, inserts the toe 7 into the front toe bar 4, and then lowers the heel 8 into the back release 5, snapping the boot 6 into place. The boot 6 comprises a bottom surface 6B configured to be placed on the top surface 3A of the base plate 3. Finally, fasteners (e.g., screws) 9 traverse holes in the ski 2 and the base plate 3 to attach the base plate to the ski.
The system 1 is shown with a three-dimensional axis system, wherein an axis X-X′ is along the length of the boot, subject to a roll R around the axis, an axis Y-Y′ is along the width of the boot subject to a pitch P around the axis, and an axis Z-Z′ along the height of the boot subject to a yaw Y around the axis.
The boot and bindings of a second foot are not shown for the sake of simplicity, but they may consist of the same elements, and be either in front of or behind the ensemble shown in the figure (along the X-X′ axis), or else next to the ensemble shown (along the Y-Y′ axis), or even not present.
Since the waterski industry is relatively small yet requires a large range of sizes and widths to fit the feet of men and women, adults and children, the hard-shell boots sold for waterskiing are generally inline skating boots. Nevertheless, inline skating boots have narrow bottom surfaces 6B to match the form of the foot, creating a good connection between the base of the foot and the skate wheels. Nevertheless, when such boots are repurposed for waterskiing, there is only a small area of contact between the bottom surface 6B of the boot and the top surface 3A of the base plate 3. The back release 5 pushes the boot 6 towards the front toe bar 4 but is unable to prevent roll R around the X-X′ axis, inducing a diminished control of the ski 2. Furthermore, “unexpected releases” may occur when the boot slides horizontally out of the binding, due to “play” or “slack” between the front toe bar 4 and the back release 5, which can worsen over time.